U.S. patent number 7,885,658 [Application Number 11/014,288] was granted by the patent office on 2011-02-08 for method for detecting reverse link collisions on an air interface.
This patent grant is currently assigned to Alcatel-Lucent USA Inc.. Invention is credited to Frances Jiang, Danny Chick-Leung Lui, Lily H. Zhu, Jialin Zou.
United States Patent |
7,885,658 |
Jiang , et al. |
February 8, 2011 |
Method for detecting reverse link collisions on an air
interface
Abstract
The present invention provides a method of wireless
telecommunication. The method includes accessing information
indicative of a first mobile unit in response to a signal from the
first mobile unit, accessing information indicative of at least one
second mobile unit, and comparing the information indicative of the
first and second mobile units. The method also includes
establishing a call connection with the first mobile unit based on
the comparison of the information indicative of the first and
second mobile units.
Inventors: |
Jiang; Frances (Whippany,
NJ), Lui; Danny Chick-Leung (Belle Mead, NJ), Zhu; Lily
H. (Parsippany, NJ), Zou; Jialin (Randolph, NJ) |
Assignee: |
Alcatel-Lucent USA Inc. (Murray
Hill, NJ)
|
Family
ID: |
36118249 |
Appl.
No.: |
11/014,288 |
Filed: |
December 16, 2004 |
Prior Publication Data
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|
|
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Document
Identifier |
Publication Date |
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US 20060135161 A1 |
Jun 22, 2006 |
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Current U.S.
Class: |
455/437; 370/342;
455/435.1; 455/450; 370/335; 455/552.1; 455/445; 455/419 |
Current CPC
Class: |
H04W
48/02 (20130101) |
Current International
Class: |
H04W
36/00 (20090101) |
Field of
Search: |
;455/450,419,551,552.1,410,411,433,435.1,436,550.1
;370/335,342 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
International European Search Report EP 05 25 7615 dated Apr. 18,
2006. cited by other.
|
Primary Examiner: Ly; Nghi H
Assistant Examiner: Mehra; Inder P
Attorney, Agent or Firm: Williams, Morgan & Amerson,
P.C.
Claims
What is claimed:
1. A method of communicating with at least a first mobile unit and
at least a second mobile unit, comprising: receiving the signal
from the first mobile unit at a first base station; accessing
information indicative of the first mobile unit; accessing
information indicative of said at least one second mobile unit;
comparing the information indicative of the first and second mobile
units; and establishing a call connection with the first mobile
unit based on the comparison of the information indicative of the
first and second mobile units, wherein the second mobile unit has
an active call connection with the first base station, and wherein
establishing a call connection comprises establishing a call
connection between the first mobile unit and a second base station
when a portion of the information indicative of the first mobile
unit is the same as a portion of the information indicative of the
second mobile unit.
2. The method of claim 1, wherein accessing the information
indicative of the first mobile unit comprises accessing at least
one of an electronic serial number and a pseudo-electronic serial
number.
3. The method of claim 1, wherein accessing the information
indicative of the first mobile unit in response to the signal from
the first mobile unit comprises accessing the information
indicative of the first mobile unit in response to at least one of
an origination signal, a page response, and a handoff admission
request.
4. The method of claim 1, wherein accessing the information
indicative of the at least one second mobile unit comprises
accessing at least one of an electronic serial number and a
pseudo-electronic serial number.
5. The method of claim 1, wherein accessing the information
indicative of the at least one second mobile unit comprises
accessing information indicative of one or more second mobile units
having active calls in a sector associated with the first mobile
unit.
6. The method of claim 5, wherein accessing the information
indicative of the at least one second mobile unit comprises
accessing information indicative of one or more second mobile units
having active calls in a sector neighboring the sector associated
with the first mobile unit.
7. The method of claim 1, wherein accessing the information
indicative of the second mobile unit comprises accessing a database
including the information indicative of at least one second mobile
unit.
8. The method of claim 1, wherein comparing the information
indicative of the first and second mobile units comprises comparing
at least one of an electronic serial number and a pseudo-electronic
serial number associated with the first and second mobile
units.
9. The method of claim 8, wherein comparing the information
indicative of the first and second mobile units comprises
determining whether the information indicative of the first and
second mobile units is an electronic serial number or a
pseudo-electronic serial number.
10. The method of claim 8, wherein comparing the information
indicative of the first and second mobile units comprises
determining whether the electronic serial number or the
pseudo-electronic serial number associated with the first mobile
unit is the same as the electronic serial number or the
pseudo-electronic serial number associated with the second mobile
unit.
11. The method of claim 1, wherein establishing a call connection
comprises denying a call connection with the first mobile unit when
a portion of the information indicative of the first mobile unit is
the same as a portion of the information indicative of the second
mobile unit.
12. The method of claim 1, wherein at least one of the information
indicative of the first mobile unit and the information indicative
of the second mobile unit comprises information indicative of a
pseudo-electronic serial number formed by combining a fixed bit
pattern with a number generated using a hashing algorithm.
13. The method of claim 1, wherein establishing the call connection
with the first mobile unit comprises establishing, using the
pseudo-electronic serial number, a call connection between the
first base station and the first mobile unit when the comparison of
the information indicative of the first and second mobile units
indicates that the call connection avoids collision at the first
base station with another call associated with the second mobile
unit.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to telecommunication systems, and,
more particularly, to wireless telecommunication systems.
2. Description of the Related Art
The coverage area of a wireless communication system is typically
divided into a number of cells, which may be grouped into one or
more networks. Mobile units located in each cell may access the
wireless communications system by establishing a wireless
communication link, often referred to as an air interface, with a
base station associated with the cell. The mobile units may include
devices such as mobile telephones, personal data assistants, Global
Positioning System devices, desktop or laptop computers, and the
like. For example, a mobile telephone may initiate communication
with a base station by providing a signal on an access channel. The
base station may then use the received access channel signal to
establish the wireless communication link between the mobile unit
and the base station on a separate traffic channel. The mobile unit
and the base station may then exchange messages over the air
interface using the traffic channel.
At any given time, each base station may be expected to maintain
concurrent wireless communication links with numerous mobile units.
To reduce interference between the concurrent wireless
communication links, the base station and the mobile units in the
wireless communication system modulate signals transmitted on the
assigned traffic channels using a predetermined code that uniquely
identifies the mobile unit. For example, in a wireless
communication system operating according to the CDMA 2000 standard,
a public long code mask may be used to differentiate reverse link
transmissions, i.e. from the mobile unit to the base station, over
different traffic channels. The public long code mask is typically
a 42-bit-long mask including two bits that indicate the type of
long code mask (e.g. public or private), an additional eight bits
that provide signaling information such as the method used to form
the long code mask, and a 32-bit electronic serial number (often
referred to using the acronym ESN) assigned to the mobile unit.
The proliferation of various types of mobile units has begun to
exhaust the supply of 32-bit electronic serial numbers. To
accommodate the growing number of mobile units, many practitioners
have proposed replacing the 32-bit electronic serial number with a
56-bit mobile equipment identifier (often referred to using the
acronym MEID: Mobile Equipment IDentifier). Under this proposal, a
56-bit mobile equipment identifier will be assigned to each mobile
unit. For example, a unique 56-bit mobile equipment identifier may
be incorporated into the hardware and/or software of each mobile
unit. The 56-bit mobile equipment identifier, or another unique bit
sequence formed based on the 56-bit mobile equipment identifier,
may then be used by base stations to uniquely identify each mobile
unit.
However, as use of the 56-bit mobile equipment identifier is phased
in over time, many legacy systems may continue to use the public
long code masks generated using the 32-bit electronic serial
number. For example, a legacy base station may generate a public
long code mask using the 32-bit electronic serial number.
Accordingly, protocols that incorporate the 56-bit mobile equipment
identifier typically provide for a pseudo-electronic serial number
(sometimes referred to as a pseudo-ESN). For example, mobile units
that operate according to the IS-2000 Revision-D standard protocol
are able to form a 32-bit pseudo-ESN using a hashing algorithm to
generate a 24-bit number and then combining this number with a
leading 8-bit fixed pattern 10000000, which is sometimes referred
to as a manufacture code. The pseudo-ESN can be used by a base
station to distinguish Revision-D mobile units from pre-Revision-D
mobile units using the 8-bit fixed pattern.
A pseudo-ESN may also be used to generate a public long code mask
that may be used to identify the mobile unit to a legacy base
station. For example, the pseudo-ESN may be used to generate a
public long code mask that may be used to identify the mobile unit
to a network that operates according to IS-2000 protocol revisions
having a protocol revision number less than 11. However, the
pseudo-ESNs, as well as the public long code masks generated using
the pseudo-ESNs, may not uniquely identify each mobile unit to the
base station. An air interface collision may therefore occur when
two mobile units in the same sector (or in neighboring sectors)
attempt to communicate with a base station on different traffic
channels within the same carrier using the same public long code
mask generated from a pseudo-ESN.
Air interface collisions may increase the frame error rate (or bit
error rate) on the reverse link. The increased frame error rate may
also cause the power control system in the base station to raise
the transmission powers used in the mobile in an attempt to
decrease the frame error rate. Since the frame error rate is
caused, at least in part, by the air interface collision, raising
the transmission power of the mobile units may exacerbate the
effects of the air interface collision and increase the frame error
rate. Thus, attempting to address the errors caused by the air
interface collision by raising the transmission power may lead to a
feedback loop that forces the mobile units and/or base stations to
transmit at their maximum transmission power. Increasing the
transmission power, potentially to the maximum transmission power
available to the mobile units and/or base stations, in this manner
may decrease overall system capacity.
Air interface collisions may also create crosstalk on the reverse
link, particularly if the signal transmitted on the traffic channel
by one of the mobile stations is much stronger than the signal
transmitted by the other mobile station. Crosstalk may also result
in a real or perceived reduction in call privacy. In some cases,
air interface collisions may also result in dropped calls, a
decrease in user-perceived quality of service, and other
undesirable effects.
The present invention is directed to addressing the effects of one
or more of the problems set forth above.
SUMMARY OF THE INVENTION
The following presents a simplified summary of the invention in
order to provide a basic understanding of some aspects of the
invention. This summary is not an exhaustive overview of the
invention. It is not intended to identify key or critical elements
of the invention or to delineate the scope of the invention. Its
sole purpose is to present some concepts in a simplified form as a
prelude to the more detailed description that is discussed
later.
In one embodiment of the present invention, a method is provided
for wireless telecommunication. The method includes accessing
information indicative of a first mobile unit in response to a
signal from the first mobile unit, accessing information indicative
of at least one second mobile unit, and comparing the information
indicative of the first and second mobile units. The method also
includes establishing a call connection with the first mobile unit
based on the comparison of the information indicative of the first
and second mobile units.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention may be understood by reference to the following
description taken in conjunction with the accompanying drawings, in
which like reference numerals identify like elements, and in
which:
FIG. 1 shows a wireless telecommunication system, in accordance
with the present invention;
FIG. 2 conceptually illustrates one embodiment of a 32-bit
electronic serial number and one embodiment of a 32-bit
pseudo-electronic serial number;
FIG. 3 conceptually illustrates one embodiment of a modified legacy
base station that can detect and/or handle potentially non-unique
identifying information that may be provided by non-legacy mobile
units, in accordance with the present invention;
FIG. 4 conceptually illustrates a method of detecting and/or
handling potentially non-unique identifying information, in
accordance with the present invention; and
FIG. 5 conceptually illustrates one embodiment of a method for
detecting potentially non-unique information identifying a first
mobile unit and establishing a call connection associated with the
first mobile unit, in accordance with the present invention.
While the invention is susceptible to various modifications and
alternative forms, specific embodiments thereof have been shown by
way of example in the drawings and are herein described in detail.
It should be understood, however, that the description herein of
specific embodiments is not intended to limit the invention to the
particular forms disclosed, but on the contrary, the intention is
to cover all modifications, equivalents, and alternatives falling
within the spirit and scope of the invention as defined by the
appended claims.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
Illustrative embodiments of the invention are described below. In
the interest of clarity, not all features of an actual
implementation are described in this specification. It will of
course be appreciated that in the development of any such actual
embodiment, numerous implementation-specific decisions should be
made to achieve the developers' specific goals, such as compliance
with system-related and business-related constraints, which will
vary from one implementation to another. Moreover, it will be
appreciated that such a development effort might be complex and
time-consuming, but would nevertheless be a routine undertaking for
those of ordinary skill in the art having the benefit of this
disclosure.
Portions of the present invention and corresponding detailed
description are presented in terms of software, or algorithms and
symbolic representations of operations on data bits within a
computer memory. These descriptions and representations are the
ones by which those of ordinary skill in the art effectively convey
the substance of their work to others of ordinary skill in the art.
An algorithm, as the term is used here, and as it is used
generally, is conceived to be a self-consistent sequence of steps
leading to a desired result. The steps are those requiring physical
manipulations of physical quantities. Usually, though not
necessarily, these quantities take the form of optical, electrical,
or magnetic signals capable of being stored, transferred, combined,
compared, and otherwise manipulated. It has proven convenient at
times, principally for reasons of common usage, to refer to these
signals as bits, values, elements, symbols, characters, terms,
numbers, or the like.
It should be borne in mind, however, that all of these and similar
terms are to be associated with the appropriate physical quantities
and are merely convenient labels applied to these quantities.
Unless specifically stated otherwise, or as is apparent from the
discussion, terms such as "processing" or "computing" or
"calculating" or "determining" or "displaying" or the like, refer
to the action and processes of a computer system, or similar
electronic computing device, that manipulates and transforms data
represented as physical, electronic quantities within the computer
system's registers and memories into other data similarly
represented as physical quantities within the computer system
memories or registers or other such information storage,
transmission or display devices.
Note also that the software implemented aspects of the invention
are typically encoded on some form of program storage medium or
implemented over some type of transmission medium. The program
storage medium may be magnetic (e.g., a floppy disk or a hard
drive) or optical (e.g., a compact disk read only memory, or "CD
ROM"), and may be read only or random access. Similarly, the
transmission medium may be twisted wire pairs, coaxial cable,
optical fiber, or some other suitable transmission medium known to
the art. The invention is not limited by these aspects of any given
implementation.
The present invention will now be described with reference to the
attached figures. Various structures, systems and devices are
schematically depicted in the drawings for purposes of explanation
only and so as to not obscure the present invention with details
that are well known to those skilled in the art. Nevertheless, the
attached drawings are included to describe and explain illustrative
examples of the present invention. The words and phrases used
herein should be understood and interpreted to have a meaning
consistent with the understanding of those words and phrases by
those skilled in the relevant art. No special definition of a term
or phrase, i.e., a definition that is different from the ordinary
and customary meaning as understood by those skilled in the art, is
intended to be implied by consistent usage of the term or phrase
herein. To the extent that a term or phrase is intended to have a
special meaning, i.e., a meaning other than that understood by
skilled artisans, such a special definition will be expressly set
forth in the specification in a definitional manner that directly
and unequivocally provides the special definition for the term or
phrase.
Referring now to FIG. 1, a wireless telecommunication system 100 is
shown. The illustrated embodiment of the wireless telecommunication
system 100 includes a plurality of base stations 105(1-3) that
provide wireless telecommunication services to an associated
geographic area 110(1-3), commonly referred to as cells 110(1-3) or
sectors. Although the cells 110 are depicted in FIG. 1 as
non-overlapping hexagons, persons of ordinary skill in the art
should appreciate that this is an idealization used for
illustrative purposes and that in practice the cells 110(1-3) may
have a variety of irregular shapes that may or may not overlap with
neighboring cells 110(1-3). Persons of ordinary skill in the art
should also appreciate that techniques for providing wireless
telecommunication services are well known and, in the interest of
clarity, only those aspects of providing wireless telecommunication
services relevant to the present invention will be discussed
herein.
In operation, the base stations 105(1-3) may establish one or more
wireless telecommunication links 115(1-3), commonly referred to as
air interfaces 115(1-3), with one or more mobile units 120(1-3).
The air interfaces 115 (1-3) may be used to transmit various
control and/or data signals such as pilot signals, paging signals,
page response signals, data packets, voice packets, and the like.
The air interfaces 115 (1-3) may operate according to one or more
protocols including, but not limited to, a Universal Mobile
Telephone System (UMTS) protocol, a Code Division Multiple Access
(CDMA 2000) protocol, a Global System for Mobile communications
(GSM) protocol, and the like. In various alternative embodiments,
the air interfaces 115(1-3) may also operate according to wireless
protocols such as a Bluetooth protocol, an 802.11 protocol, and the
like.
Each mobile unit 120(1-3) is associated with information that
uniquely identifies the mobile unit 120(1-3). In one embodiment,
the mobile units 120(1-3) are each associated with a unique 56-bit
mobile equipment identifier (often referred to using the acronym
MEID: Mobile Equipment IDentifier). In various alternative
embodiments, the 56-bit mobile equipment identifier may be
incorporated into the hardware and/or software of each mobile unit
120(1-3). The mobile units 120(1-3) may provide the 56-bit mobile
equipment identifier, or another unique bit sequence formed based
on the 56-bit mobile equipment identifier, to the base stations
105(1-3) to uniquely identify each mobile unit 120(1-3).
In the illustrated embodiment, the base station 105(1) is a legacy
base station. As used herein, the term "legacy" refers to systems
that expect to receive a 32-bit electronic serial number, or some
permutation of the 32-bit electronic serial number, from the mobile
units 120(1-3). Legacy systems also assume that the 32-bit
electronic serial number, or the expected permutation thereof,
uniquely identifies the mobile units 120(1-3). For example, the
legacy base station 105(1) expects to receive a public long code
mask formed using a 32-bit electronic serial number provided by the
mobile unit 120(1) and also expects the public long code mask to
uniquely identify the mobile unit 120(1). Examples of legacy
systems include wireless telecommunication systems that operate
according to IS-2000 protocol revisions having a protocol revision
number less than 11, wireless telecommunication systems that
operate according to versions of the IS-2000 standard protocol
prior to Revision-D, and the like.
Accordingly, the mobile units 120(1-3) may form and provide a
pseudo-electronic serial number (sometimes referred to as a
pseudo-ESN) based on the 56-bit mobile equipment identifier. For
example, mobile units 120(1-3) that operate according to the
IS-2000 Revision-D standard protocol are able to form a 32-bit
pseudo-ESN using a hashing algorithm to generate a 24-bit number
and then combining this number with a leading 8-bit fixed pattern,
which is sometimes referred to as a manufacture code. For example,
the manufacture code may be set to 10000000.
FIG. 2 conceptually illustrates one embodiment of a 32-bit
electronic serial number 200 and one embodiment of a 32-bit
pseudo-electronic serial number 205. The electronic serial number
200 includes 32 bits 210, which may be set to "1" or "0" to
identify an associated mobile unit. For example, the electronic
serial number 200 may be used to generate a public long code mask
that may be used to identify a mobile unit to a legacy base
station. The pseudo-electronic serial number 205 includes a
plurality of identifying bits 215 and a leading fixed pattern 220
of a plurality of fixed bits 225. For example, the
pseudo-electronic serial number 205 includes 24 identifying bits
215 and a leading fixed pattern 220 of eight fixed bits 225. The
pseudo-electronic serial number 205 may also be used to generate a
public long code mask that may be used to identify the mobile unit
to a legacy base station. For example, the pseudo-electronic serial
number 205 may be used to generate a public long code mask that may
be used to identify a mobile unit to a network that operates
according to IS-2000 protocol revisions having a protocol revision
number less than 11. However, the pseudo-electronic serial number
205, as well as the public long code masks generated using the
pseudo-electronic serial number 205, may not uniquely identify each
mobile unit to the network. Thus, air interface collisions may
occur when two mobile units in the same sector (or in neighboring
sectors) attempt to communicate with a base station on different
traffic channels within the same carrier using the same public long
code mask generated from an identical pseudo-ESN. For example, air
interface collisions may occur when two mobile units having
identical pseudo-ESNs attempt to originate calls with a base
station, respond to a page from a base station, during call
handoff, and the like.
Referring back to FIG. 1, additional mobile units may provide
signals to the base station 105(1) on a reverse link, such as
origination signals, page response signals, handoff requests, and
the like. In one embodiment, a mobile unit 125 in the cell 110(1)
provides an origination signal indicating that the mobile unit 125
would like to establish a call connection with the base station
105(1). Alternatively, the mobile unit 125 may provide a response
to a page signal broadcast by the base station 105(1). In another
embodiment, the mobile unit 120(2) may move from the cell 110(2) to
the cell 110(1). Accordingly, the base station 105(1) may receive a
request to handoff a call connection associated with the mobile
unit 120(2). As discussed above, the mobile units 125, 120(2)
provide a pseudo-electronic serial number, or other identifying
information, to the base station 105(1), which may use the
identifying information to generate a public long code mask. Since
the pseudo-electronic serial number provided to the base station
105(1) may not uniquely identify the mobile units 125, 120(2), the
base station 105(1) is modified to detect and/or handle the
potentially non-unique identifying information.
FIG. 3 conceptually illustrates one embodiment of a base station
105(1) that can detect and/or handle potentially non-unique
identifying information that may be provided by mobile units. In
the illustrated embodiment, the base station 105(1) includes the
transmitter 305 and a receiver 310 that may be used to transmit
and/or receive signals using an antenna 315, in a manner well known
to persons of ordinary skill in the art. The transmitter 305 and
the receiver 310 are coupled to a controller 320, which is coupled
to a database 330 having a plurality of entries 335. In one
embodiment, the entries 335 include information indicative of one
or more mobile units having active call connections with the base
station 105(1). However, the present invention is not limited to
databases 330 including entries 335 corresponding to mobile units
having active call stations with the base station 300. In
alternative embodiments, the database 330 may include entries 335
corresponding to any desirable mobile units, such as mobile units
having active call connections with neighboring base stations.
FIG. 4 conceptually illustrates a method 400 of detecting and/or
handling potentially non-unique identifying information. Referring
now to FIGS. 1, 3, and 4, in the illustrated embodiment, the base
station 105(1) can access (at 405) identifying information, such as
the pseudo-electronic serial number or public long code mask,
associated with the mobile units 125, 120(2) in response to
receiving the origination signal, page response, handoff request,
or other signal from the mobile unit 125, 120(2). The base station
105(1) can also access (at 410) information indicative of other
mobile units associated with the base station 105(1). For example,
the base station 105(1) may access the database 330 containing
entries 335 having information indicative of mobile units 120(1)
having active call connections with the base station 105(1). Active
call connections in neighboring cells 110(2-3) may contribute to
interference and/or crosstalk within the cell 110(1). Thus, in one
embodiment, the database 330 may also include entries 335 having
information indicative of mobile units in the neighboring cells
110(2-3). For example, the base station 105(1) may access
information indicative of the mobile unit 120(3) in the database
330. In various alternative embodiments, the information indicative
of the various mobile units 120(1-3), 125 stored in the database
330 may include an electronic serial number, a pseudo-electronic
serial number, a public long code mask, and the like.
The base station 105(1) compares (at 415) the information
indicative of the mobile units 125, 120(2) to the information
indicative of the mobile units 120(1, 3) having active call
connections. For example, the base station 105 (1) may compare (at
415) a pseudo-electronic serial number provided by the mobile unit
125 to an electronic serial number provided by the mobile unit 120
(1). The base station 105(1) then establishes (at 420) one or more
call connections with the mobile units 125, 120(2) based on the
comparison.
FIG. 5 conceptually illustrates one embodiment of a method 500 for
detecting a potentially non-unique identifier associated with a
first mobile unit and establishing a call connection (or granting a
handoff admission request) with the first mobile unit. In the
illustrated embodiment, a first base station has access to
electronic serial numbers associated with the first mobile unit and
at least one second mobile unit. For example, the first mobile unit
may provide the electronic serial number on an access channel and
the electronic serial number(s) of the second mobile units may be
stored in a database. One or more of the second mobile units may
have active call connections established with the first base
station on a first carrier frequency. As discussed above, the
present invention is not limited to comparing electronic serial
numbers and, in alternative embodiments, the information indicative
of the first and/or second mobile units may include a
pseudo-electronic serial number, a public long code mask, and the
like.
The first base station compares (at 505) the electronic serial
number associated with the first mobile unit to each of the
electronic serial numbers associated with the at least one second
mobile unit. If the electronic serial number associated with the
first mobile unit is different from all of the electronic serial
numbers associated with second mobile units, the first base station
establishes (at 510) a call connection between the first mobile
unit and the first base station.
If the first base station determines (at 505) that the first
electronic serial number is the same as at least one of the second
electronic serial numbers, indicating that a call connection
between the first mobile unit and the first base station on the
first carrier frequency may lead to an air interface collision, the
first base station determines (at 515) whether or not a second
carrier frequency is available. If a second carrier frequency is
available, the first base station may establish (at 520) a call
connection with the first mobile unit on the second carrier
frequency. If the first base station determines (at 515) that a
second carrier frequency, or other channel, is not available, the
first base station may determine (at 525) whether or not a second
base station is available to handle a call connection with the
first mobile unit. If a second base station is available to handle
a call connection with the first mobile unit, then a call
connection may be established (at 530) between the second base
station and the first mobile unit. However, if no additional base
stations are available, the call connection requested by the first
mobile unit may be denied (at 535).
Implementing one or more embodiments of the above invention may
reduce air interface collisions, such as may be caused by using
non-unique mobile unit identifiers in legacy systems. Embodiments
of the invention described above may be implemented in software
and/or hardware, or any combination thereof. Moreover, the
implementations may be incorporated into existing legacy systems
without upgrading the entire system to remove legacy equipment.
The particular embodiments disclosed above are illustrative only,
as the invention may be modified and practiced in different but
equivalent manners apparent to those skilled in the art having the
benefit of the teachings herein. Furthermore, no limitations are
intended to the details of construction or design herein shown,
other than as described in the claims below. It is therefore
evident that the particular embodiments disclosed above may be
altered or modified and all such variations are considered within
the scope and spirit of the invention. Accordingly, the protection
sought herein is as set forth in the claims below.
* * * * *